Aromatic compounds and their compositions for the control of insect pests

ABSTRACT

An aromatic compound of the formula: ##STR1## wherein R 1  and R 2  are, the same or different, a hydrogen atom, a halogen atom or a methyl group with the proviso that either one of R 1  or R 2  is a hydrogen atom; R 3  is a hydrogen atom or a methyl group; and R 4  is a halogen atom, a C 1  -C 2  alkyl group or a C 1  -C 2  haloalkyl group, which is useful for control of insect pests.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to aromatic compounds, their production processes and their compositions for the control of insect pests.

2. Description of the Prior Art

It is described in U.S. Pat. Nos. 3,987,102, 4,094,989 and 4,153,731 that certain aromatic compounds are useful as insecticides and acaricides. But, their insecticidal and acaricidal activities are still not satisfactory.

SUMMARY OF THE INVENTION

As a result of the extensive study seeking aromatic compounds producing a satisfactory controlling effect on insect pests, it has been found that those of the following formula exhibit a remarkable juvenile hormone-like activity and can control significantly the growth of insect pests: ##STR2## wherein R¹ and R² are, the same or different, a hydrogen atom, a halogen atom or a methyl group with the proviso that either one of R¹ or R² is a hydrogen atom; R³ is a hydrogen atom or a methyl group; and R⁴ is a halogen atom, a C₁ -C₂ alkyl group or a C₁ -C₂ haloalkyl group. The present invention is based on the above finding.

DETAILED DESCRIPTION OF THE INVENTION

The aromatic compounds (I) of the invention have an excellent juvenile hormone-like activity against insect pests. They exhibit various actions such as metamorphosis inhibition, embryogenesis inhibition and sterilization and are thus efficacious as growth regulators, chemosterilants, ovicides or reproduction inhibitory agents on various insect pests such as agricultural, forestal, hygienic and stored grain insect pests. They are also efficacious against insect pests having an increased resistance to commercial insecticides.

In the formula (I) which represents the aromatic compounds of the invention, examples of the halogen atom are chlorine, bromine, fluorine, iodine, etc. Examples of the C₁ -C₂ haloalkyl group include trifluoromethyl, difluoromethyl, 2-fluoroethyl, 1-fluoroethyl, 1,2-difluoroethyl, 2,2,2-trifluoroethyl and 2-chloroethyl, etc.

Among the aromatic compounds (I), preferred are those wherein R¹ and R² are, the same or different, a hydrogen atom, a halogen atom or a methyl group with the proviso that either one of R¹ or R² is a halogen atom or a methyl group; R³ is a hydrogen atom; and R⁴ is a halogen atom or a C₁ -C₂ haloalkyl group. More preferred are those wherein R¹ is a fluorine atom, a chlorine atom or a methyl group; R² is a hydrogen atom; R³ is a hydrogen atom; and R⁴ is a chlorine atom.

The aromatic compounds (I) of the invention can be produced by various processes, among which typical examples are shown below.

Process A:

The aromatic compound (I) is produced by reacting a phenol compound of the formula: ##STR3## wherein M is an alkali metal atom or a hydrogen atom and R¹ and R² are each as defined above with a halide of the formula: ##STR4## wherein A is a halogen atom and R³ and R⁴ are each as defined above.

The reaction may be carried out usually in an inert solvent in the presence of a base at a temperature of from about -20° C. to the boiling point of the solvent, preferably from about -5° C. to the boiling point of the solvent. When the phenol compound (II) is employed in a metal salt form, the base is not necessarily required to use.

The molar proportion of the phenol compound (II) and the halide (III) to be used for the reaction is not limitative but is preferred to be nearly equal. Examples of the inert solvent are lower alcohols (e.g. methanol, ethanol, propanol, isopropanol, tert-butanol), ketones (e.g. acetone, methyl ethyl ketone), hydrocarbons (e.g. hexane, benzene, toluene), ethers (e.g. diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane), acid amides (e.g. N,N-dimethylformamide, hexamethylphosphoric triamide), halogenated hydrocarbons (e.g. dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene), nitriles (e.g. acetonitrile), nitro compounds (e.g. nitromethane), dimethyl sulfoxide, sulfolane, water and mixtures thereof. Example of the base are alkali metal hydroxides (e.g. sodium hydroxide, potassium hydroxide), alkali metal carbonates (e.g. sodium carbonate, potassium carbonate), alkali metals (e.g. metallic sodium), alkali metal hydrides (e.g. sodium hydride), organic bases (e.g. sodium methoxide, sodium ethoxide, triethylamine, pyridine), etc. When necessary or desired, an ammonium salt such as triethylbenzylammonium chloride and tetrabutylammonium bromide may be added to the reaction system as a catalyst.

After completion of the reaction, post-treatment may follow in a per se conventional manner such as extraction with an organic solvent and concentration. When necessary or desired, the product may further be purified by chromatography, distillation, recrystallization, etc.

Process B:

The aromatic compound (I) is produced by reacting a phenol compound of the formula: ##STR5## wherein R¹ and R² are each as defined above with an alcohol of the formula: ##STR6## wherein R³ and R⁴ are each as defined above. This process is advantageously applicable when R³ is other than a hydrogen atom.

The reaction may be carried out normally in an inert solvent in the presence of a dehydrating catalyst or agent at a temperature of from about -20° to 200° C. or the boiling point of the inert solvent.

The molar proportion of the phenol compound (IV) and the alcohol (V) is not limitative but is preferred to be nearly equal. Examples of the dehydrating catalyst are inorganic acids (e.g. hydrochloric acid, sulfuric acid), aromatic sulfonic acids, sulfonic acid halides, etc. Examples of the dehydrating agent include dicyclohexylcarbodimide, diisopropyl azodicarboxylate with triphenylphosphine, diethyl azodicarboxylate with triphenylphosphine, etc. Examples of the inert solvent are hydrocarbons (e.g. benzene, toluene, xylene), ethers (e.g. diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane), halogenated hydrocarbons (e.g. carbon tetrachloride, dichloromethane, 1,2-dichloroethane, chlorobenzene, dichlorobenzene), etc.

After completion of the reaction, post-treatment may follow in a per se conventional manner such as extraction with an organic solvent and concentration. When necessary or desired, the product may further be purified by chromatography, distillation, recrystallization, etc.

The aromatic compounds (I) of the invention have some asymmetric carbon atoms and can form optical isomers. Those optical isomers and their mixtures fall within the scope of the invention.

Among the starting compounds in the above processes, the phenol compound (II) wherein M is an alkali metal atom can be preprared from the corresponding phenol compound (IV) (i.e. the compound of the formula (II) wherein M is a hydrogen atom).

The phenol compound (IV) are available on the commercial market or can be readily produced from appropriate commercial products.

The phenol compound (IV) may be prepared by reacting the corresponding non-chlorinated compound, i.e. a phenol compound, of teh formula: ##STR7## wherein R¹ and and R² are each as defined above with a chlorinating agent, preferably in an inert solvent.

The molar proportion of the phenol compound (VI) and the chlorinating agent is not limitative but it is ordinary to use the chlorinating agent in an amount equivalent to the phenol compound (VI) or somewhat in excess. Examples of the chlorinating agent are chlorine, tert-butyl hypochlorite, sulfuryl chloride, etc. If necessary and desired, the reaction can be carried out in the presence of an inert solvent. Examples of the solvent are dichloromethane, 1,2-dichloroethane, carbon tetrachloride, benzene, acetic acid, etc. The chlorinating agent itself may be available as a reaction medium when it is liquid. The reaction temperature is usually from about -80° C. to the refluxing temperature of the reaction system, preferably from about -20° C. to the refluxing temperature of the reaction system.

After completion of the reaction, post-treatment may follow in a per se conventional manner such as extraction with an organic solvent and concentration. When necessary or desired, the product may further be purified by chromatography, distillation, recrystallization, etc.

Further, the phenol compound (VI) is obtainable from appropriate commercial products (e.g. substituted phenol, substituted halobenzene) by a conventional procedure as shown below. ##STR8## wherein R¹ and R² are each as defined above, Ha is a halogen atom and R⁵ is a hydrogen atom or a methyl group.

Among the starting compounds in the above processes, the halide (III) and the alcohol (V) are available on the commercial market or can be readily produced from appropriate commercial products by the known method as described in Chem.Ber., 89, 1732 (1956), J.Amer.Chem.Soc., 76, 908 (1954), etc.

Examples of the aromatic compounds (I) of the present invention are shown in Table 1.

                  TABLE 1                                                          ______________________________________                                          ##STR9##                                                                      R.sup.1     R.sup.2    R.sup.3    R.sup.4                                      ______________________________________                                         H           H          H          F                                            H           H          H          Cl                                           H           H          H          Br                                           H           H          H          I                                            H           H          H          CH.sub.3                                     H           H          H          C.sub.2 H.sub.5                              H           H          H          CF.sub.3                                     H           H          H          C.sub.2 F.sub.5                              F           H          H          F                                            F           H          H          Cl                                           F           H          H          Br                                           F           H          H          I                                            F           H          H          CH.sub.3                                     F           H          H          C.sub.2 H.sub.5                              F           H          H          CF.sub.3                                     F           H          H          C.sub.2 H.sub.5                              Cl          H          H          F                                            Cl          H          H          Cl                                           Cl          H          H          Br                                           Cl          H          H          I                                            Cl          H          H          CH.sub.3                                     Cl          H          H          C.sub.2 H.sub.5                              Cl          H          H          CF.sub.3                                     Cl          H          H          CH.sub.2 Br                                  Cl          H          H          C.sub.2 F.sub.5                              Br          H          H          F                                            Br          H          H          Cl                                           Br          H          H          Br                                           Br          H          H          I                                            Br          H          H          CH.sub.3                                     Br          H          H          C.sub.2 H.sub.5                              Br          H          H          CF.sub.3                                     Br          H          H          C.sub.2 F.sub.5                              I           H          H          F                                            I           H          H          Cl                                           I           H          H          Br                                           I           H          H          I                                            I           H          H          CH.sub.3                                     I           H          H          C.sub.2 H.sub.5                              I           H          H          CF.sub.3                                     I           H          H          C.sub.2 F.sub.5                              CH.sub.3    H          H          F                                            CH.sub.3    H          H          Cl                                           CH.sub.3    H          H          Br                                           CH.sub.3    H          H          I                                            CH.sub.3    H          H          CH.sub.3                                     CH.sub.3    H          H          C.sub.2 H.sub.5                              CH.sub.3    H          H          CF.sub.3                                     CH.sub.3    H          H          C.sub.2 F.sub.5                              H           F          H          F                                            H           F          H          Cl                                           H           F          H          Br                                           H           F          H          I                                            H           F          H          CH.sub.3                                     H           F          H          C.sub.2 H.sub.5                              H           F          H          CF.sub.3                                     H           F          H          C.sub.2 F.sub.5                              H           Cl         H          F                                            H           Cl         H          Cl                                           H           Cl         H          Br                                           H           Cl         H          I                                            H           Cl         H          CH.sub.3                                     H           Cl         H          C.sub.2 H.sub.5                              H           Cl         H          CF.sub.3                                     H           Cl         H          C.sub.2 F.sub.5                              H           Br         H          F                                            H           Br         H          Cl                                           H           Br         H          Br                                           H           Br         H          I                                            H           Br         H          CH.sub.3                                     H           Br         H          C.sub.2 H.sub.5                              H           Br         H          CF.sub.3                                     H           Br         H          C.sub.2 F.sub.5                              H           I          H          F                                            H           I          H          Cl                                           H           I          H          Br                                           H           I          H          I                                            H           I          H          CH.sub.3                                     H           I          H          C.sub.2 H.sub.5                              H           I          H          CF.sub.3                                     H           I          H          C.sub.2 F.sub.5                              H           CH.sub.3   H          F                                            H           CH.sub.3   H          Cl                                           H           CH.sub.3   H          Br                                           H           CH.sub.3   H          I                                            H           CH.sub.3   H          CH.sub.3                                     H           CH.sub.3   H          C.sub.2 H.sub.5                              H           CH.sub.3   H          CF.sub.3                                     H           CH.sub.3   H          C.sub.2 F.sub.5                              F           H          CH.sub.3   F                                            F           H          CH.sub.3   Cl                                           F           H          CH.sub.3   Br                                           F           H          CH.sub.3   I                                            F           H          CH.sub.3   CH.sub.3                                     F           H          CH.sub.3   C.sub.2 H.sub.5                              F           H          CH.sub.3   CF.sub.3                                     F           H          CH.sub.3   C.sub.2 F.sub.5                              Cl          H          CH.sub.3   F                                            Cl          H          CH.sub.3   Cl                                           Cl          H          CH.sub.3   Br                                           Cl          H          CH.sub.3   I                                            Cl          H          CH.sub.3   CH.sub.3                                     Cl          H          CH.sub.3   C.sub.2 H.sub.5                              Cl          H          CH.sub.3   CF.sub.3                                     Cl          H          CH.sub.3   C.sub.2 F.sub.5                              Br          H          CH.sub.3   F                                            Br          H          CH.sub.3   Cl                                           Br          H          CH.sub.3   Br                                           Br          H          CH.sub.3   I                                            Br          H          CH.sub.3   CH.sub.3                                     Br          H          CH.sub.3   C.sub.2 H.sub.5                              Br          H          CH.sub.3   CF.sub.3                                     Br          H          CH.sub.3   C.sub.2 F.sub.5                              I           H          CH.sub.3   F                                            I           H          CH.sub.3   Cl                                           I           H          CH.sub.3   Br                                           I           H          CH.sub.3   I                                            I           H          CH.sub.3   CH.sub.3                                     I           H          CH.sub.3   C.sub.2 H.sub.5                              I           H          CH.sub.3   CF.sub.3                                     I           H          CH.sub.3   C.sub.2 F.sub.5                              CH.sub.3    H          CH.sub.3   F                                            CH.sub.3    H          CH.sub.3   Cl                                           CH.sub.3    H          CH.sub.3   Br                                           CH.sub.3    H          CH.sub.3   I                                            CH.sub.3    H          CH.sub.3   CH.sub.3                                     CH.sub.3    H          CH.sub.3   C.sub.2 H.sub.5                              CH.sub.3    H          CH.sub.3   CF.sub.3                                     CH.sub.3    H          CH.sub.3   C.sub.2 F.sub.5                              H           F          CH.sub.3   F                                            H           F          CH.sub.3   Cl                                           H           F          CH.sub.3   Br                                           H           F          CH.sub.3   I                                            H           F          CH.sub.3   CH.sub.3                                     H           F          CH.sub.3   C.sub.2 H.sub.5                              H           F          CH.sub.3   CF.sub.3                                     H           F          CH.sub.3   C.sub.2 F.sub.5                              F           Cl         CH.sub.3   F                                            F           Cl         CH.sub.3   Cl                                           F           Cl         CH.sub.3   Br                                           F           Cl         CH.sub.3   I                                            F           Cl         CH.sub.3   CH.sub.3                                     F           Cl         CH.sub.3   C.sub.2 H.sub.5                              F           Cl         CH.sub.3   CF.sub.3                                     F           Cl         CH.sub.3   C.sub.2 F.sub.5                              H           Br         CH.sub.3   F                                            H           Br         CH.sub.3   Cl                                           H           Br         CH.sub.3   Br                                           H           Br         CH.sub.3   I                                            H           Br         CH.sub.3   CH.sub.3                                     H           Br         CH.sub.3   C.sub.2 H.sub.5                              H           Br         CH.sub.3   CF.sub.3                                     H           Br         CH.sub.3   C.sub.2 F.sub.5                              H           I          CH.sub.3   F                                            H           I          CH.sub.3   Cl                                           H           I          CH.sub.3   Br                                           H           I          CH.sub.3   I                                            H           I          CH.sub.3   CH.sub.3                                     H           I          CH.sub.3   C.sub.2 H.sub.5                              H           I          CH.sub.3   CF.sub.3                                     H           I          CH.sub.3   C.sub.2 F.sub.5                              H           CH.sub.3   CH.sub.3   F                                            H           CH.sub.3   CH.sub.3   Cl                                           H           CH.sub.3   CH.sub.3   Br                                           H           CH.sub.3   CH.sub.3   I                                            H           CH.sub.3   CH.sub.3   CH.sub.3                                     H           CH.sub.3   CH.sub. 3  C.sub.2 H.sub.5                              H           CH.sub.3   CH.sub.3   CF.sub.3                                     H           CH.sub.3   CH.sub.3   C.sub.2 F.sub.5                              H           H          CH.sub.3   F                                            H           H          CH.sub.3   Cl                                           H           H          CH.sub.3   Br                                           H           H          CH.sub.3   I                                            H           H          CH.sub.3   CH.sub.3                                     H           H          CH.sub.3   C.sub.2 H.sub.5                              H           H          CH.sub.3   CF.sub.3                                     H           H          CH.sub.3   C.sub.2 F.sub.5                              ______________________________________                                    

Examples of the insect pests against which the aromatic compounds (I) of the invention exhibit controlling effects are as shown below.

Hemiptera:

Planthoppers such as brown planthopper (Nilaparvata lugens), white-backed rice planthopper (Sogatella furcifera) and small brown planthopper (Laodelphax striatellus); leafhoppers such as green rice leafhopper (Nephotettix cincticeps), Nephotettix virescense, Nephotettix nigropictus, zig-zag rice leafhopper (Recilia dorsalis), tea green leafhopper (Empoasca onukii) and grape leafhopper (Arboridia apicalis); aphids such as cotton aphid (Aphis gossypii) and green peach aphid (Myzus persicae); bugs; whiteflies (Aleyrodidae) such as sweet potato whitefly (Bemisia tabaci) and greenhouse whitefly (Trialeurodes vaporariorum); scales; mealy bugs; lace bugs (Tingidae); psyllids (Psyllidae), etc.

Lepidoptera:

Pyralid moths (Pyralidae) such as rice stem borer (Chilo suppressalis), rice leafroller (Cnaphalocrocis medinalis) and Indian meal moth (Plodia interpunctella); Noctuidae such as tobacco curworm (Spodoptera litura), rice armyworm (Pseudaletia separate), cabbage armyworm (Mamestra brassicae) and beet semi-looper (Autographa nigrisigna); Agrothis spp. such as turnip cutworm (Agrothis segetum) and black cutworm (Agrothis ipsilon); Heliothis spp.; Pieridae such as common cabbageworm (Pieris rapae crucivora); tortricid moths (Tortricidae) such as Adoxophyes spp. and Grapholita spp.; Carposinidae such as lyonetiid moths (Lyonetiidae), leafblotch miners (Gracillariidae), gelechiid moths (Gelechiidae) and tussock moths (Lymantriidae); diamondback moth (Plutella xylostella), clothes moths (Tineidae), casemaking clothes moth (Tinea translucens) and webbing clothes moth (Tineola bisselliella), etc.

Diptera:

Mosquitos (Calicidae) such as common mosquito (Culex pipiens pallens) and Culex tritaeniorhynchus; Aedes spp. such as Aedes aegypti and Aedes albopictus; Anopheles spp. such as Anopheles sinensis; midges (Chironomidae); Muscidae such as housefly (musca domestica) and false stablefly (Muscina stabulans); Calliphoridae; Sarcophagidae; lesser housefly (Fannia canicularis); anthomyiid flies (Anthomyiidae) such as seedcorn maggot (Delia platura) and onion maggot (Delia antique); fruit flies (Tephritidae); shore flies (Ephydridae); small fruit flies (Drosophilidae); moth flies (Psychodidae); black flies (Simuliidae); Tabanidae; stable flies (Stomoxyidae); etc.

Coleoptera:

Leaf beetles (Chrysomelidae) such as cucurbit beetle (Aulacophora femoralis), striped flea beetles (Phyllotrata striolata), western corn rootworm (Diabrotica virgifora) and southern corn root worm (Diabrotica undecimpunctata); scarabs (Scarabaeidae) such as cupreous chafer (Anomala cuprea) and soybeen beetle (Anomala rufocuprea); weevils (Cureulionidae) such as maize weevil (Sitophilus zeamais), rice water weevil (Lissorhoptrus oryzophilus) and adzuki bean weevil (Callosobruchys chineneis), etc.; darkling beetles (Tenebrionidae) such as yellow mealworm (Tenebrio moliter) and red flour beetles (Tribolium castaneum); Anobiidae; Coccinellidae such as twenty-eight-spotted ladybirds (Epilachna vigintioctopunctata); powderpost beetles (Lyctidae); false powderpost beetles (Bostrychidae); Cerambysidae, etc.

Dictyoptera:

Blattellidae such as German cockroach (Blattella germanica); Blattidae such as smokybrown cockroach (Periplaneta fuliginosa), American cockroach (Periplaneta americana), brown cockroach (Periplaneta brunnea) and oriental cockroach (Blatta orientalis), etc.

Thysanoptera:

Thrips such as Thrips palmi, yellow tea thrips (Scirtothrips dorsalis) and flower thrips (Thrips hawaiiensis), etc.

Hymenoptera:

Ants (Formicidae); sawflies (Tenthredinidae) such as cabbage sawfly (Athalia rosae ruficornis), etc.

Orthoptera:

Mole crickets (Gryllotalpidae); grasshoppers (Acrididae), etc.

Aphaniptera:

Purex irritans, etc.

Anoplura:

Pediculus humanus capitis, Phthirus pubis, etc.

Isoptera:

Reticulitermes speratus, Formosan subterrauean termite (Coptotermes formosanus), etc.

Among the insect pests as above exemplified, the aromatic compounds (I) are particularly effective in controlling those belonging to Hemiptera and also exhibit a remarkable controlling effect on planthoppers and leafhoppers in a field of rice plant.

The aromatic compounds (I) may be used alone as insecticides or in mixtures with other insecticides and/or acaricides to enhance or expand their insecticidal or pesticidal use.

Examples of the other insecticides and/or acaricide include organophosphorus compounds (e.g. fenitrothion (O,O-dimethyl O-(3-methyl-4-nitrophenyl)phosphorothioate), fenthion (O,O-dimethyl O-[3-methyl-4-(methylthio)phenyl]phosphorothioate), diazinon (O,O-diethyl-O-(2-isopropyl-6-methyl-pyrimidin-4-yl)phosphorothioate), chlorpyrifos (O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)phosphorothioate), acephate (O,S-dimethyl acetylphosphoramidothioate), methidathion (S-2,3-dihydro-5-methoxy-2-oxo-1,3,4-thiadiazol-3-ylmethyl O,O-dimethylphosphorodithioate), disulfoton (O,O-diethyl S-2-ethylthioethyl phosphorothioate), DDVP (2,2-dichlorovinyldimethylphosphate), sulprofos (O-ethyl O-4-(methylthio)phenyl S-propyl phosphorodithioate), cyanophos (O-4-cyanophenyl O,O-dimethyl phosphorothioate), dioxabenzofos (2-methoxy-4H-1,3,2-benzodioxaphosphinine-2-sulphide), dimethoate (O,O-diethyl-S-(N-methylcarbamoylmethyl)dithiophosphate), phenthoate (ethyl 2-dimethoxyphosphinothioylthio(phenyl)acetate), malathion (diethyl (dimethoxyphosphinothioylthio)succinate), trichlorfon (dimethyl 2,2,2-trichloro-1-hydroxyethylphosphonate), azinphos-methyl (S-3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-ylmethyl O,O-dimethylphosphoro-dithioate) and monocrotophos (dimethyl (E)-1-methyl-2-(methylcarbamoyl)vinyl phosphate), etc.); carbamate derivatives (e.g. BPMC (2-sec-butylphenyl methylcarbamate), benfuracarb (ethyl N-[2,3-dihydro-2,2-dimethylbenzofuran-7-yloxycarbonyl-(methyl)aminothio]-N-isopropyl-beta-alaninate), propoxur (2-isopropoxyphenyl N-methylcarbamate), carbosulfan (2,3-dihydro-2,2-dimethyl-7-benzo[b]furanyl N-methylcarbamate), carbaryl (1-naphthyl-N-methylcarbamate), methomyl (S-methyl-N-[(methylcarbamoyl)oxy]thioacetimidate), ethiofencarb (2-(ethylthiomethyl)phenyl methylcarbamate), aldicarb (2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime) and Oxamyl (N,N-dimethyl-2-methylcarbamoyloxyimino-2-(methylthio)acetamide), etc.); pyrethroides (e.g. ethofenprop (2-(4-ethoxyphenyl-2-methylpropyl-3-phenoxybenzylether), fenvalerate ((RS)-alpha-cyano-3-phenoxybenzyl (RS)-2-(4-chlorophenyl)-3-methylbutyrate), esfenvalerate ((S)-alpha-cyano-3-phenoxybenzyl (S)-2-(4-chlorophenyl)-3-methylbutyrate), fenpropathrin ((RS)-alpha-cyano-3-phenoxybenzyl 2,2,3,3-tetramethylcyclopropanecarboxylate), cypermethrin ((RS)-alpha-cyano-3-phenoxybenzyl (1RS,3RS)-(1RS,3RS)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate), permethrin (3-phenoxybenzyl (1RS,3RS)-(1RS,3RS)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate), cyhalothrin ((R,S)-alpha-cyano-3-phenoxybenzyl (Z)-(1RS,3RS)-3-(2-chloro-3,3,3-trifluoropropenyl)-2,2-dimethylcyclopropanecarboxylate), deltamethrin ((S)-alpha-cyano-m-phenoxybenzyl (1R,3R)-3-(2,2-dibromovinyl)-2-dimethylcyclopropanecarboxylate) and cycloprothrin ((RS)-alpha-cyano-3-phenoxybenzyl (RS)-2,2-dichloro-1-(4-ethoxyphenyl)cyclopropanecarboxylate), etc.); thiadiazine derivatives (e.g. buprofezin (2-tert-butylimino-3-isopropyl-5-phenyl-1,3,5-triadiazin-4-one), etc.); nitroimidazolidine derivatives (e.g. imidacloprid (1-(6-chloro-3-pyridylmethyl)-N-nitro-imidazolidin-2-ylideneamine), etc.); nereistoxin derivatives (e.g. cartap (S,S'-(2-dimethylaminotrimethylene) bis(thiocarbamate), thiocyclam (N,N-dimethyl-1,2,3-trithian-5-ylamine) and bensultap (S,S'-2-dimethylaminotrimethylene di(benzenethiosulphonate), etc.); halogenated hydrocarbons (e.g. endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide) and gamma-BHC (1,2,3,4,5,6-hexachlorocyclohexane), etc.); benzoylphenylurea derivatives (e.g. chlorfluazuron (1-[3,5-dichloro-4-(3-chloro-5-trifluoromethylpyridin-2-yloxy)phehyl]-3-(2,6-difluorobenzoyl)urea), teflubenzuron (1-(3,5-dichloro-2,4-difluorophenyl)-3-(2,6-difluorobenzoyl)urea) and flufenoxuron (1-[4-(2-chloro-4-trifluoromethylphenoxy)-2-fluorophenyl]-3-(2,6-difluorobenzoyl)urea, etc.); formamidine derivatives (e.g. amitraz (N,N'-[(methylimino)dimethylidyne]-di-2,4-xylidine) and chlordimeform (N'-(4-chloro-2-methylphenyl)-N,N-dimethylmethanimidamide), etc.).

On the practical use of the aromatic compounds (I) as insecticides, they may be employed as such but are normally mixed with appropriate additives such as solid carriers, liquid carriers, gaseous carriers, feed, etc. to formulate their compositions. When desired or necessary, surfactants and other adjuvants may be further incorporated therein. The compositions may be prepared into any conventional forms such as oil sprays, emulsifiable concentrates, wettable powders, flowable concentrates (e.g. water-based suspension formulations, water-based emulsion formulations), granules, dusts, aerosals, heating smoking formulations (e.g. self-burning-type smoking formulations, chemical reaction-type smoking formulations, porous ceramic plate-type smoking formulations), ULV formulations, poison baits, etc.

The composition of the invention contains generally the aromatic compound(s) (I) as the active ingredient in an amount of from about 0.001% to 95% by weight based on the composition.

Examples of the solid carrier usable for making the composition are fine powders or granules of clays (e.g. kaolin clay, diatomaceous earth, synthetic hydrated silica, bentonite, Fubasami clay, terra alba), talc, ceramics, other inorganic minerals (e.g. sericite, quartz, sulfur, activated carbon, calcium carbonate, hydrated silica), chemical fertilizers (e.g. ammonium sulfate, ammonium phosphate, ammonium nitrate, urea, ammonium chloride), etc. Examples of the liquid carrier include water, alcohols (e.g. methanol, ethanol), ketones (e.g. acetone, methyl ethyl ketone), aromatic hydrocarbons (e.g. benzene, toluene, xylene, ethylbenzene, methylnaphthalene), aliphatic hydrocarbons (e.g. hexane, cyclohexane, kerosene, gas oil), esters (e.g. ethyl acetate, butyl acetate), nitriles (e.g. acetonitriles, isobutyronitrile), ethers (e.g. diisopropyl ether, dioxane), acid amides (e.g. N,N-dimethylformamide, N,N-dimethylacetamide), halogenated hydrocarbons (e.g. dichloromethane, trichloroethane, carbon tetrachloride), dimethylsulfoxide, vegetable oils (e.g. soybean oil, cotton seed oil), etc. Examples of the gaseous carrier, i.e. a propellant, include freon gas, butane gas, LPG (liquefied petroleum gas), dimethyl ether, carbon dioxide, etc.

Examples of the surfactant are alkylsulfates, alkylsulfonates, alkylarylsulfonates, alkyl aryl ethers and polyoxyethylene derivatives thereof, polyethylene glycol ethers, polyvalent alcohol esters, sugar alcohol derivatives, etc. Examples of the adjuvants such as binders and dispersing agents are casein, gelatin, polysaccharides (e.g. starch powders, gum arabic, cellulose derivatives, alginic acid), lignin derivatives, bentonite, sugars, synthetic water-soluble high molecular weight substances (e.g. polyacrylic alcohol, polyvinylpyrrolidone, polyacrylic acid), etc. Examples of the stabilizer include PAP (acidic isopropyl phosphate), BHT (2,6-di-tert-butyl-4-methylphenol), BHA (mixture of 2-tert-butyl-4-methoxyphenol and 3-tert-butyl-4-methoxyphenol), vegetable oils, mineral oils, surfactants, fatty acids or esters thereof, etc.

The base material for self-burning-type smoking formulations may include, for example, burning heat-generating agents such as nitrates, nitrites, guanidine salts, potassium chlorate, nitrocellulose, ethyl cellulose and wood powders, pyrolysis-promoting agents such as alkali metal salts, alkaline earth metal salts, dichromates and chromates, oxygen-supplying agents such as potassium nitrate, burning-supporting agents such as melamine and wheat starch, extenders such as diatomaceous earth, binders such as synthetic pastes, etc. The base material for chemical reation-type smoking formulations can include, for example, heat-generating agents such as alkali metal sulfides, alkali metal polysulfides, alkali metal hydrosulfides, hydrated salts of alkali metals and calcium oxide, catalyzing agents such as carbonaceous substances, iron carbide and activated clay, organic foaming agents such as azodicarbonamide, benzenesulfonyl hydrazides, dinitrosopentamethylenetetramine, polystyrene and polyurethane, fillers such as natural fiber pieces and synthetic fiber pieces, etc. The base material for poison baits may contain feed components such as crop powders, essential vegetable oil, sugars and crystalline cellulose, antioxidants such as dibutylhydroxyrtolune and nordihydroguaiaretic acid, preservatives such as dehydroacetic acid, feeding error preventing agnets such as red paper powders, incentive flavors such as cheese flavor and onion flavor, etc.

Flowable concentrates (water-based suspension or emulsion formulations) are generally obtained by dispersing about 1 to 75 parts by weight of the aromatic compound (I) as the active ingredient finely and uniformly into water containing about 0.5 to 15 parts by weight of a dipersing agent, about 0.1 to 10 parts by weight of a suspending agent (e.g. protective colloids, compounds giving a thixotropic property) and optionally about 0 to 10 parts by weight of an auxiliary agent(s) such as a defoaming agent, an anti-corrosive agent, a stabilizing agent, a spreading agents, penetration auxiliaries, antifreezing agent, an anti-bacterial agent, an antimolding agent and the like. The use of an oil, into which the active ingredient is hardly soluble, in place of water affords oil-based suspension formulations. Examples of the protective colloids as above mentioned are gelatin, casein, gums, cellulose ethers, polyvinyl alcohol, etc. Examples of the compounds giving a thixotropic property are bentonite, aluminum magnesium silicate, xanthane gum, polyacrylic acid, etc.

The composition of the invention thus obtained may be used as such or after diluting with water. It may be also used in a mixture with any other active component or composition chosen from insecticides, nematocides, acaricides, fungicides, bacteriocides, herbicides, plant growth regulators, synergistic agents, fertilizers, soil conditioners, animal feed, etc. Alternatively, the composition of the invention may be applied separately but simultaneously with said other active component or composition.

For the purpose of controlling insect pests in the agricultural field, the aromatic compound (I) according to the present invention may be applied to the insect pests or the locus where the insect pests propagate generally in an amount of about 0.001 g to 500 g, and preferably about 0.1 g to 500 g per 10 ares. When the aromatic compound (I) is applied in a form of emulsifiable concentrate, wettable powder, flowable concentrate or the like after dilution with water, its concentration may be from about 0.0001 to 1000 ppm. Granules, dusts, etc. may be used as such, i.e. without water dilution. When the aromatic compound (I) is used for household or public hygiene, it may be used in the form of emulsifiable concentrate, wettable powder, flowable concentrate or the like with water dilution, etc. In this case, the concentration of the active ingredient may be from about 0.0001 to 10,000 ppm. In case of oils, aerosol, fumigants, ULV formulations, poison baits, etc., they may be applied as such. However, the doses and concentrations may vary within broad ranges depending upon the composition, the application time, the place applied, the application method, the kind of insect pests, the condition of damage, etc. and may be increased or decreased, irrespective of the general ranges set forth above.

Practical and presently preferred embodiments of the invention will be hereinafter explained in more detail referring to Production Examples, Formulation Examples and Test Examples. These examples, however, should not be construed to be limitative.

In the following Production Examples, % is by weight unless otherwise indicated.

PRODUCTION EXAMPLE 1 Production of Compound No. 6

To a solution of 0.07 g of sodium hydride (60% oil dispersion) in 10 ml of N,N-dimethylformamide, there was added dropwise a solution of 0.40 g of 2-chloro-4-(3-chlorophenoxy)phenol in 3 ml of N,N-dimethylformamide with stirring and ice-cooling. After 10 minutes, a solution of 0.25 g of p-chlorobenzyl chloride in 5 ml of N,N-dimethylformamide was added thereto at room temperature, followed by stirring at the same temperature for 10 hours. The reaction mixture was poured into ice-water and extracted twice with 100 ml of ethyl acetate. The extracts were combined together, washed with water, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel chromatography to give 0.48 g of 4-chloro-1-[2-chloro-4-(3-chlorophenoxy)phenoxy]methylbenzene. Yield, 81%. m.p., 72.1° C.

PRODUCTION EXAMPLE 2 Production of Compound No. 8

A mixture of 0.88 g of 2-chloro-4-(3-fluorophenoxy)phenol, 0.54 g of p-chlorobenzyl alcohol, 1.01 g of triphenylphosphine, 0.65 g of diethylazadicarboxylate and 90 ml of tetrahydrofuran was stirred at room temperature. After 48 hours, the reaction mixture was concentrated, and 50 ml of diethyl ether was added thereto. The precipitates were removed by filtration, and the filtrate was concentrated. The residue was subjected to silica gel chromatography to give 0.83 g of 4-chloro-1-[2-chloro-4-(3-fluorophenoxy)phenoxy]methylbenzene. Yield, 62%. m.p., 47.3° C.

Some examples of the aromatic compounds (I) as produced in the same manner as above are shown in Table 2.

                                      TABLE 2                                      __________________________________________________________________________     Compound No.                                                                           Chemical structure            Physical constant                        __________________________________________________________________________              ##STR10##                    n.sub.D .sup.25.5 1.5980                 2                                                                                       ##STR11##                    n.sub.D .sup.25.0 1.5932                 3                                                                                       ##STR12##                    m.p., 65.9° C.                    4                                                                                       ##STR13##                    m.p., 82.0° C.                    5                                                                                       ##STR14##                    n.sub.D .sup.27.0 1.6040                 6                                                                                       ##STR15##                    m.p., 72.1° C.                    7                                                                                       ##STR16##                    n.sub.D .sup.25.0 1.5904                 8                                                                                       ##STR17##                    m.p., 47.3° C.                    9                                                                                       ##STR18##                    m.p., 60.6° C.                    10                                                                                      ##STR19##                    n.sub.D .sup.25.0 1.6022                 11                                                                                      ##STR20##                    n.sub.D .sup.25.0 1.5747                 12                                                                                      ##STR21##                    m.p., 30.2° C.                    13                                                                                      ##STR22##                    m.p., 77.4° C.                    14                                                                                      ##STR23##                    m.p., 94.9° C.                    __________________________________________________________________________

In Formulation Examples as set forth below, parts and % are all by weight. The compound numbers correspond to those as shown in Table 2.

FORMULATION EXAMPLE 1 Emulsifiable Concentrate

To a solution of 10 parts of each of Compounds Nos. 1 to 14 in 35 parts of xylene and 35 parts of dimethylformamide, 14 parts of polyoxyethylene styrylphenyl ether and 6 parts of calcium dodecylbenzenesulfonate are added, and the resultant mixture is thoroughly mixed while stirring to give an emulsifiable concentrate containing the active ingredient in 10%.

FORMULATION EXAMPLE 2 Wettable Powder

Twenty parts of each of Compounds Nos. 1 to 14 are added to a mixture of 4 parts of sodium laurylsulfate, 2 parts of calcium ligninsulfonate, 20 parts of fine powders of synthetic hydrated silica and 54 parts of diatomaceous earth, and the resultant mixture is stirred in a mixer to give a wettable powder containing the active ingredient in 20%.

FORMULATION EXAMPLE 3 Granules

Five parts of sodium dodecylbenzenesulfonate, 30 parts of bentonite and 60 parts of clay are added to 5 parts of each of Compound Nos. 1, 2, 5, 7, 10 and 11, and the resultant mixture is pulverized and kneaded with a suitable amount of water. The mixture is granulated in a granulator and air-dried to give granules containing the active ingredient in 5%.

FORMULATION EXAMPLE 4 Granules

Five parts of fine powders of synthetic hydrated silica, 5 parts of sodium dodecylbenzenesulfonate, 30 parts of bentonite and 55 parts of clay are added to 5 parts of each of Compound Nos. 3, 4, 6, 8, 9, 12, 13 and 14, and the resultant mixture is pulverized and kneaded with a suitable amount of water. The mixture is granulated in a granulator and air-dried to give granules containing the active ingredient in 5%.

FORMULATION EXAMPLE 5 Dusts

To a mixture of 1 part of fine powders of synthetic hydrated silica, 1 part of an aggregating agent ("Driless B" manufactured by Sankyo Co., Ltd.) and 7.7 parts of clay, 0.3 part of each of Compound Nos. 1, 2, 5, 7, 10 and 11 is added, and the resultant mixture is well pestled in a mortar and further stirred in a mixer. To the thus obtained mixture, there are added 90 parts of cut clay, followed by mixing to give dusts containing the active ingredient in 0.3%.

FORMULATION EXAMPLE 6 Dusts

A mixture of 0.3 part of each of Compound Nos. 3, 4, 6, 8, 9, 12, 13 and 14 and 0.03 part of fine powders of synthetic hydrated silica is stirred well in a mixer and pulverized by the aid of a centrifugal pulverizer. To the resultant mixture, 0.97 part of fine powders of synthetic hydrated silica, 1 part of "Driless B" and 7.7 parts of clay are added, and the resulting mixture is pestled in a mortar and stirred in a mixer. Ninety parts of cut clay are added thereto, and further mixing is effected in a sack to give dusts containing the active ingredient in 0.3%.

FORMULATION EXAMPLE 7 Dusts

A mixture of 0.3 part of each of Compound Nos. 1, 2, 5, 7, 10 and 11, 2 parts of fenitrothion (O,O-dimethyl O-(3-methyl-4-nitrophenyl)phosphorothioate as an organophosphorus insecticide, 3 parts of fine powders of synthetic hydrated silica, 1 part of "Driless B" and 3.7 parts of clay are pestled in a mortar and stirred in a mixer. Then, 90 parts of cut clay are added thereto, and the resultant mixture is further mixed in a sack to give dusts.

FORMULATION EXAMPLE 8 Dusts

A mixture of 0.3 part of each of Compound Nos. 3, 4, 6, 8, 9, 12, 13 and 14 and 0.03 part of fine powders of synthetic hydrated silica is stirred in a mixer and pulverized by a centrifugal pulverizer. After addition of 2 parts of fenitrothion, 2.97 parts of fine powders of synthetic hydrated silica, 1 part of "Driless B" and 3.7 parts of clay thereto, the resultant mixture is pestled in a mortar and stirred in a mixer. Then, 90 parts of cut clay are added thereto, and the resultant mixture is further mixed in a sack to give dusts.

FORMULATION EXAMPLE 9 Dusts

A mixture of 0.3 part of each of Compound Nos. 1, 2, 5, 7, 10 and 11, 2 parts of BPMC (O-sec-butylphenyl N-methylcarbamate) as a carbamate insecticide, 3 parts of fine powders of synthetic hydrated silica, 1 part of "Driless B" and 3.7 parts of clay are pestled in a mortar and stirred in a mixer. Then, 90 parts of cut clay are added thereto, and the resultant mixture is further mixed in a sack to give dusts.

FORMULATION EXAMPLE 10 Dusts

A mixture of 0.3 part of each of Compound Nos. 3, 4, 6, 8, 9, 12, 13 and 14 and 0.03 part of fine powders of synthetic hydrated silica is stirred in a mixer and pulverized by a centrifugal pulverizer. After addition of 2 parts of BPMC, 2.97 parts of fine powders of synthetic hydrated silica, 1 part of "Driless B" and 3.7 parts of clay thereto, the resultant mixture is pestled in a mortar and stirred in a mixer. Then, 90 parts of cut clay are added thereto, and the resultant mixture is further mixed in a sack to give dusts.

FORMULATION EXAMPLE 11 Dusts

To a solution of 1 part of each of Compound Nos. 1 to 14 in an appropriate amount of acetone, 5 parts of fine powders of synthetic hydrated silica, 0.3 part of PAP (acidic isopropyl phosphate) and 93.7 parts of clay are added, and the resultant mixture is stirred in a mixer, followed by evaporation of acetone to give dusts containing the active ingredient in 1%.

FORMULATION EXAMPLE 12 Flowable Concentrate

To 40 parts of an aqueous solution containing 2 parts of polyvinyl alcohol, 10 parts of each of Compound Nos. 1, 2, 5, 7, 10 and 11 are added, and the resultant mixture is stirred in a mixer. To the thus obtained dispersion, 40 parts of an aqueous solution containing 0.05 part of xanthane gum and 0.1 part of aluminum magnesium silicate are added, followed by addition of 10 parts of propylene glycol. The mixture is gently stirred to give a flowable concentrate containing the active ingredient in 10%.

FORMULATION EXAMPLE 13 Flowable Concentrate

To 28.5 parts of an aqueous solution containing 2 parts of polyvinyl alcohol, 20 parts of each of Compound Nos. 3, 4, 6, 8, 9, 12, 13 and 14 and 1.5 parts of sorbitan trioleate are added, and the resultant mixture is finely pulverized by the aid a sand grinder to give particles of less than 3 microns in average particle size. To the resultant mixture, 40 parts of an aqueous solution containing 0.05 part of xanthane gum and 0.1 part of aluminum magnesium silicate are added, followed by addition of 10 parts of propylene glycol. The mixture is gently stirred to give a flowable concentrate containing the active ingredient in 20%.

FORMULATION EXAMPLE 14 Oil Spray

Into a mixture of 5 parts of xylene and 5 parts of trichloroethane, 0.1 part of each of Compound Nos. 1 to 14 is dissolved, and the resultant solution is mixed with 89.9 parts of deodorized kerosene to give an oil spray containing the active ingredient in 0.1%.

FORMULATION EXAMPLE 15 Oil-Based Aerosol

A solution of 0.1 part of each of Compound Nos. 1 to 14, 0.2 part of tetramethrin (2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylic acid (1,2,3,4,5,7-hexahydro-1,3-dioxo-2H-isoindol-2-yl)methyl ester) and 0.1 part of d-phenothrin (2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylic acid (3-phenoxyphenyl)methyl ester) in a mixture of 10 parts of trichloroethane and 59.6 parts of deodorized kerosene is filled in an aerosol container. After provision of a valve, 30 parts of a propellant (liquefied petroleum gas) is filled through the valve under compression to give an oil-based aerosol.

FORMULATION EXAMPLE 16 Water-Based Aerosol

A solution of 0.2 part of each of Compound Nos. 1 to 14, 0.2 part of d-allethrin ((2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylic acid 2-methyl-4-oxo-3-(2-propenyl)-2-cyclopenten-2-yl ester), 0.2 part of d-phenothrin, 5 parts of xylene, 3.4 parts of deodorized kerosene and 1 part of an emulsifier ("ATMOS 300"®, Atlas Chemical Co., Ltd.) in 50 parts of distilled water is filled in an aerosol container. After provision of a valve, 40 parts of a propellant (liquefied petroleum gas) is filled through the valve under compression to give a water-based aerosol.

FORMULATION EXAMPLE 17 Fumigant

Each of Compound Nos. 1 to 14 (100 mg) is dissolved in an appropriate amount of acetone, and the resultant solution is impregnated with a porous ceramic plate (4.0×4.0×1.2 cm) to give a fumigant.

The following Test Examples show some of test results which support the controlling effect of the aromatic compounds (I) on insect pests. The compound numbers correspond to those as shown in Table 2. The compounds used for comparison are as follows:

    ______________________________________                                         Compound                                                                       symbol  Chemical structure     Remarks                                         ______________________________________                                                  ##STR24##             Compound disclosed in U.S. Pat. No.                                            3,987,102                                       ______________________________________                                    

TEST EXAMPLE 1

Metamorphosis inhibitory activity against brown rice planthopper nymphs:

An emulfiable concentrate prepared according to Formulation Example 1 was diluted with water to make a predetermined concentration. The dilution was sprayed onto rice plants cultivated in polyethylene cups at a rate of 20 ml/2 pots on a turning table. After air-drying, the plants were infested with about ten 3rd instar nymphs of brown rice planthopper (Nilaparvata lugens). After 10 days, the number of normal adults was counted to obtain an emergence inhibitory rate. The results are shown in Table 3.

                  TABLE 3                                                          ______________________________________                                         Compound                   Inhibitory                                          No.         Concentration (ppm)                                                                           rate (%)                                            ______________________________________                                         1           50             100                                                 2           5              100                                                 3           50             100                                                 4           5              100                                                 5           50             100                                                 6           5              100                                                 7           50             100                                                 8           5              100                                                 9           50             100                                                 10          5              100                                                 11          50             100                                                 12          5              100                                                 13          50             100                                                 14          5              100                                                 A           50              25                                                 ______________________________________                                    

Compound Nos. 3, 4, 6, 8, 9, 12, 13 and 14 also showed a 100% emergence inhibition at a concentration of 500 and 50 ppb.

TEST EXAMPLE 2

Reproduction inhibitory activity against green rice leafhopper:

An emulfiable concentrate prepared according to Formulation Example 1 was diluted with water to make a predetermined concentration. The dilution was sprayed onto rice plants (about 20 cm in height) cultivated in plastic pots (1/5000 are in width) at a rate of 40 ml/2 pots on a turning table. After air-drying, the pots were covered with wire cages, and each 10 male and female adults of green rice leafhopper (Nephotettix cincticeps) were released in each of the cages. After 3 weeks, the number of nymphs was counted to obtain a reproduction inhibitory rate. The results are shown in Table 4.

                  TABLE 4                                                          ______________________________________                                         Compound                   Inhibitory                                          No.         Concentration (ppm)                                                                           rate (%)                                            ______________________________________                                         6           100            100                                                 8           100            100                                                 9           100            100                                                 A           100             0                                                  ______________________________________                                    

TEST EXAMPLE 3

Reproduction inhibitory activity against brown rice planthopper:

An emulfiable concentrate prepared according to Formulation Example 1 was diluted with water to make a predetermined concentration. The dilution was sprayed onto rice plants (about 20 cm in height) cultivated in plastic pots (1/5000 are in width) at a rate of 40 ml/2 pots on a turning table. After air-drying, the pots were covered with wire cages, and each 5 female and male adults of brown rice planthopper (Nilaparvata lugens) were released in each of the cages. After about 3 weeks, the number of nymphae was counted to obtain a reproduction inhibitory rate. The results are shown in Table 5.

                  TABLE 5                                                          ______________________________________                                         Compound                   Inhibitory                                          No.         Concentration (ppm)                                                                           rate (%)                                            ______________________________________                                         6           100            99                                                  8           100            99                                                  A           100             0                                                  ______________________________________                                     

What is claimed is:
 1. An aromatic compound of the formula: ##STR25## wherein R¹ and R² are the same or different and are each a hydrogen atom, a halogen atom or a methyl group, with the proviso that either one of R¹ or R² is a hydrogen atom; R³ is a hydrogen atom or a methyl group; and R⁴ is a halogen atom, a C₁ -C₂ alkyl group or a C₁ -C₂ haloalkyl group.
 2. The aromatic compound according to claim 1, wherein either one of R¹ or R² is a halogen atom or a methyl group; R³ is a hydrogen atom; and R⁴ is a halogen atom or a C₁ -C₂ haloalkyl group.
 3. The aromatic compound according to claim 1, wherein R¹ is a fluorine atom, a chlorine atom or a methyl group; R² is a hydrogen atom; R³ is a hydrogen atom; and R⁴ is a chlorine atom.
 4. The aromatic compound according to claim 1, which is 1-[2-chloro-4-(3-chlorophenoxy)phenoxy]methyl-4-trifluoromethylbenzene.
 5. The aromatic compound according to claim 1, which is 4-chloro-1-[2-chloro-4-(3-fluorophenoxy)phenoxy]methylbenzene.
 6. The aromatic compound according to claim 1, which is 4-chloro-1-[2-chloro-4-(3-methylphenoxy)phenoxy]methylbenzene.
 7. The aromatic compound according to claim 1, which is 4-chloro-1-[1-(2-chloro-4-phenoxyphenoxy]ethylbenzene.
 8. The aromatic compound according to claim 1, which is 4-bromo-1-[2-chloro-4-(3-chlorophenoxy)phenoxy]methylbenzene.
 9. The aromatic compound according to claim 1, which is 4-chloro-1-[1-(2-chloro-4-(4-chlorophenoxy)phenoxy]methylbenzene.
 10. The aromatic compound according to claim 1, which is 4-chloro-1-[2-chloro-4-(3-chlorophenoxy)phenoxy]methylbenzene.
 11. The aromatic compound according to claim 1 of the formula ##STR26##
 12. The aromatic compound according to claim 1 of the formula ##STR27##
 13. The aromatic compound according to claim 1 of the formula ##STR28##
 14. The aromatic compound according to claim 1 of the formula ##STR29##
 15. The aromatic compound according to claim 1 of the formula ##STR30##
 16. The aromatic compound according to claim 1 of the formula ##STR31##
 17. The aromatic compound according to claim 1 of the formula ##STR32##
 18. A composition for controlling insect pests which comprises an effective amount of the aromatic compound according to claim 1 and an inert carrier.
 19. A method for controlling insect pests which comprises applying an effective amount of the aromatic compound according to claim 1 to the insect pests or the locus where the insect pests propagate. 